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Table 1 (abstract P7). Multivariable models (before and after variable selection) for predicting spontaneous preterm delivery within seven days in symptomatic women

From: Methods for Evaluation of medical prediction Models, Tests And Biomarkers (MEMTAB) 2018 Symposium

  Model including all variables Model after variable selection
Beta OR (95% CI) Betaa OR (95% CI)
Intercept
 Study 1 -7.9   -4.6  
 Study 2 -8.5   -5.3  
 Study 3 -9.0   -5.7  
 Study 4 -8.7   -5.4  
 Study 5 -9.3   -6.0  
Quantitative fetal fibronectin (qfFN)b
 (qfFN+1)/100)^0.5 2.0 7.6 (5.7 – 10) 1.89 6.6 (4.9 – 8.9)
Age (yr) 0.02 1.0 (0.98 – 1.1) - -
BMI (kg/m2) 0.02 1.0 (0.96 – 1.1) - -
Smoking -0.66 0.52 (0.24 – 1.1) -0.67 0.51 (0.24 – 1.08)
Ethnicity
 1 Caucasian Reference   Reference  
 2 South Asian 1.1 2.9 (0.93 – 9.1) 0.94 2.6 (0.84 – 7.9)
 3 East Asian -1.2 0.31 (0.04 – 2.5) -1.004 0.37 (0.05 – 2.8)
 4 African, Caribbean, Middle-East -0.21 0.81 (0.42 – 1.5) -0.21 0.81 (0.43 – 1.5)
 5 Other -0.25 0.78 (0.20 – 3.0) -0.31 0.74 (0.19 – 2.8)
Nulliparity 0.53 1.7 (1.1 – 2.7) 0.37 1.4 (0.92 – 2.2)
Multiple pregnancy 0.85 2.3 (1.4 – 4.1) 0.83 2.3 (1.3 – 3.9)
Previous spontaneous
PTD < 34 weeks
0.43 1.5 (0.78 – 1.1) - -
Gestational age at assessment (wks) 0.03 1.0 (0.96 – 1.1) - -
Nagelkerke R2 0.39 0.39
AUC (95%CI) 0.90 (95% CI 0.88 – 0.93) 0.89 (95% CI 0.87 – 0.93)
  1. PTD preterm delivery < 7 days
  2. aRegression coefficients of the predictors in the model were shrunken with a uniform shrinkage factor 0.92. The intercepts were re-estimated after shrinkage of the regression coefficients of the predictors to ensure perfect calibration-in-the-large.
  3. bTransformation of continuous variable ‘quantitative fetal fibronectin’ because of non-linearity